Alzheimer’s in people younger than 65 linked to night light exposure
Researchers looked at US nighttime light pollution, Medicare records of disease
Higher exposure to outdoor light at night may increase the risk of developing Alzheimer’s disease, especially in people younger than 65, according to a study that drew on Medicare records and satellite-based light pollution maps.
“Average nighttime light intensity was more strongly associated with [Alzheimer’s disease] prevalence than some diseases and conditions reported or suspected to be risk factors for [Alzheimer’s disease],” the researchers wrote.
The study, “Outdoor nighttime light exposure (light pollution) is associated with Alzheimer’s disease,” was published in Frontiers in Neuroscience by Voigt-Zuwala and two other researchers from the Rush University Medical Center.
As people live longer due to advances in healthcare, age-related diseases like Alzheimer’s have become more common. However, environmental factors such as air and light pollution are also thought to contribute to the rise in Alzheimer’s cases.
The researchers looked at the link between nighttime light pollution in the U.S. and how common Alzheimer’s is based on Medicare records. The lower 48 states were divided into five groups based on light intensity calculated from satellite-based light pollution maps, from the darkest to the brightest.
Sleep disruption and Alzheimer’s
There was a clear link between higher exposure to outdoor light at night and increased Alzheimer’s prevalence. Regions with the brightest light intensity had a higher prevalence than those with the darkest.
Although factors like an irregular heartbeat, diabetes, high blood pressure, and stroke were more strongly linked to Alzheimer’s, nighttime light pollution was more closely linked to the disease than alcohol abuse, chronic kidney disease, and obesity.
This pattern was consistent in both men and women, and in people older than 65. However, in those younger than 65, the link with nighttime light pollution was the strongest, “suggesting that those under the age of 65 may be particularly sensitive to the effects of exposure to light at night,” the researchers wrote.
The mechanisms behind this link are still unclear, but researchers suggested that by disrupting sleep, nighttime light exposure may activate immune cells in the brain, leading to inflammation. Sleep disruption can also impair the brain’s ability to clear amyloid beta, a protein associated with Alzheimer’s. These factors may contribute to nerve cell loss and brain atrophy, affecting cognitive functions and memory.
“While data from … the current study suggest exposure to light at night may influence [Alzheimer’s], additional studies evaluating clinical and population health are needed,” the researchers wrote.
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